Decision Tree
A decision tree is a branching model used in economic evaluation: strategies, chance events and end points give each option's expected costs and QALYs.
Encyclopaedia
Explore comprehensive, evidence-informed explanations of key health economics concepts, including their development, application and relationships to other concepts. Published entries are validated through human expert review.
Concepts, entries and ontology terms
A concept page is a published entry on the wiki. Some concepts also have a full encyclopaedia article. The Health Economics Ontology (HEO) holds every concept, including dictionary terms without an article, so it is larger than the list of published pages. The knowledge graph shows how concepts relate to each other.
Decision Tree Model
A decision tree model is an economic evaluation model whose branches map each option's patient pathways to give expected costs and QALYs per strategy.
Decision Uncertainty
Decision uncertainty is the probability that the option preferred on current evidence is not the best, given uncertainty in costs and health effects.
Default Effect
The default effect is the tendency to stay with a pre-selected option, so opt-out schemes for organ donation or HIV testing raise uptake over opt-in.
Degrees of Freedom
Degrees of freedom (df) count values left free to vary after estimation and set the t, chi-squared or F curve for tests in trials and meta-analyses.
Delphi Method
The Delphi method is an expert survey run in anonymous rounds with group feedback, used in health economics to agree judgements or estimate model inputs.
Delta Method
The delta method approximates the variance of a function of estimated parameters, such as an ICER or mean survival, using a first-order Taylor expansion.
Demand for Health
Demand for health is the idea, from the Grossman model, that people value health as a capital stock, so their demand for healthcare is derived from it.
Demand Inducement
Demand inducement is a provider's use of an information advantage to shift a patient's demand for care away from the patient's best interests.
Departure Process
Departure process is the pattern of times at which patients leave a clinic, ward or other stage of care in a queueing model or discrete event simulation.
Dependent Censoring
Dependent censoring occurs when the chance of being censored is linked to a patient's risk of the event, so standard survival estimates can be biased.
Derived Demand for Healthcare
Derived demand for healthcare is the idea that people want medical care mainly as an input for producing health, the thing they actually value.
Descriptive Statistics
Descriptive statistics summarise the centre, spread and shape of data, such as skewed patient costs, whose arithmetic mean sets the total budget.
Design Effect
The design effect (DEFF) is the ratio of an estimate's variance under a clustered or complex sample to that under a simple random sample of equal size.
Deterministic Model
A deterministic model is a health economic model with no random elements, so the same inputs always give the same costs, QALYs and ICER.
Deterministic Sensitivity Analysis
Deterministic sensitivity analysis (DSA) reruns a health economic model with chosen inputs set to fixed values to see how results and decisions change.
Deviance Residual
A deviance residual is a signed measure of how poorly a generalised linear or survival model fits each patient; in a GLM its squares sum to the deviance.
Diabetes Complications
Long-term health consequences of poorly controlled diabetes, including cardiovascular disease, kidney disease, nerve damage, and eye disease.
Diagnostic Accuracy
Diagnostic accuracy is how well a test agrees with a reference standard in detecting a target condition, usually reported as sensitivity and specificity.
Diagnostic Model
A diagnostic model is a multivariable prediction model estimating the probability a condition is present now, to guide testing, referral and treatment.